Simple blood test detects heart transplant rejection

Easy assay found signs months before biopsy

Heart transplant recipients whose bodies are starting to reject the new organ might carry genetic warning signs. A new test of recipients’ blood appears as accurate in catching rejection as a heart biopsy, the current gold standard for monitoring donated hearts, researchers led by Stephen Quake and Kiran Khush of Stanford University report in the June 18 Science Translational Medicine.

The scientists scoured each heart recipient’s blood for free-floating DNA from the donor. The researchers distinguished recipient DNA from donor DNA by tracking naturally occurring genetic variations called single nucleotide polymorphisms. Donor SNPs are common the day after transplant, the researchers found, but decline within a week. After that, increases in donor DNA serve as a warning sign of rejection.

Over the course of two years, the researchers regularly tested the blood of 65 heart transplant recipients, three of whom experienced moderate to severe rejection at some point, with one requiring a second heart transplant. The new blood test revealed these episodes as much as five months before heart biopsies did. The test might enable doctors to treat impending rejection earlier in hopes of avoiding full-blown rejection and a repeat transplant, the researchers say.